JP2006158697A - Gradient magnetic field coil system and magnetic resonance imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gradient magnetic field coil shortening the axial length of a vessel for reducing the oppressive feeling of a subject and securing the linearity of the gradient magnetic field. <P>SOLUTION: The end of the cylindrical gradient magnetic field coil 2 projects from the end face of a static magnetic field generating means 1, and an annular wiring material unit 30, or a terminal processing means of the gradient magnetic field coil 2, is disposed in the outer circumferential side of the projecting part of the gradient magnetic field coil 2. The annular wiring material unit 32 is disposed in the outer circumferential part of the gradient magnetic field coil 2 to secure a space in the internal circumferential side of the gradient magnetic field coil 2, namely, secure a space where the subject is placed without narrowing it, and to axially expand the pattern area of the gradient magnetic field coil 2. This constitution can shorten the axial length of the static magnetic field generating means 1 to an approximately same length of the gradient magnetic field coil 2 and axially expand the pattern area of the gradient magnetic field coil 2 so as to secure the linearity of the magnetic field. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic field generating means for a magnetic resonance imaging apparatus, and more particularly to a gradient coil apparatus that generates a gradient magnetic field and a magnetic resonance imaging apparatus using the same.

  In a cylindrical magnetic resonance imaging apparatus (MRI apparatus), since the inner diameter of the space into which the patient is inserted is small and the axial length is long, the patient may feel uneasy.

  As a conventional technique for reducing this anxiety, Patent Document 1 describes a technique for shortening the axial length of a magnet container.

  Patent Document 2 discloses a technique for obtaining an appropriate and reliable insulation performance at the time of manufacturing with respect to cable connection to a gradient magnetic field coil.

  In the technique described in Patent Document 2, a connection terminal is disposed on the end face of the gradient magnetic field coil.

  Patent Document 3 discloses a technique for arranging a shim tray in a gradient magnetic field coil in order to perform shim adjustment in order to adjust the uniformity of a static magnetic field.

JP 60-244006 A JP 2002-085370 A US Pat. No. 5,786,695

  By the way, as described in Patent Document 2, when the connection terminal is arranged on the coil end surface, the axial length of the entire MRI apparatus is affected. The shortening technique is a contradictory technique regarding the axial length.

  Therefore, a technique for performing the connection end processing of the gradient magnetic field coil so as not to affect the axial length is required in the future.

  Further, when the magnet container is shortened as in the technique described in Patent Document 1, it is necessary to shorten the gradient magnetic field coil and the RF coil arranged inside the magnet container.

  However, the uniformity of the magnetic field generated by the gradient coil, that is, the linearity cannot be ensured by simply shortening the axial length of the gradient coil.

  In order to adjust the homogeneity of the magnetic field, it is conceivable to arrange a shim tray in the gradient magnetic field coil as described in Patent Document 3, but in this case as well, the connection end processing of the gradient magnetic field coil is performed in the axial length. There is still a problem with how to do this so as not to affect the process.

  An object of the present invention is to provide a gradient coil device capable of shortening the axial length of a container and reducing the linearity of a gradient magnetic field in order to reduce the feeling of pressure felt by a subject, and magnetic resonance using the same It is to realize an imaging apparatus.

  In order to achieve the above object, the present invention is configured as follows.

  (1) A gradient magnetic field coil apparatus according to the present invention is used in a magnetic resonance imaging apparatus having a substantially cylindrical static magnetic field generating means, and has a cylindrical gradient magnetic field disposed on the inside of the cylinder of the static magnetic field generating means. It has a coil and is supplied with current from a gradient magnetic field power source.

  And the wiring material unit which connects the said gradient magnetic field coil and the power supply for gradient magnetic fields is arrange | positioned along the said one end part outer periphery on the outer periphery of the one end part side of the said gradient magnetic field coil apparatus.

  (2) The magnetic resonance imaging apparatus of the present invention has a substantially cylindrical static magnetic field generating means and a cylindrical gradient magnetic field coil arranged on the cylinder inner side of the static magnetic field generating means, and a gradient magnetic field is applied to the subject. A gradient magnetic field generating means for supplying a gradient magnetic field, a gradient magnetic field power source for supplying a current to the gradient magnetic field generating means, an irradiation means for applying a high-frequency pulse for causing a nuclear magnetic resonance phenomenon in the subject, and an echo signal emitted from the subject. A receiving unit for detecting, an operation control unit for performing an image reconstruction calculation using an echo signal detected by the receiving unit and controlling an imaging operation, and a display unit for displaying an image are provided.

  In the magnetic resonance imaging apparatus of the present invention, the wiring material unit that connects the gradient magnetic field coil and the gradient magnetic field power source to the outer periphery on one end side of the cylindrical gradient magnetic field coil extends along the outer periphery on the one end side. Are arranged.

  (3) Preferably, in the above (1) and (2), the wiring member unit is formed integrally with the gradient magnetic field coil.

  (4) Preferably, in the above (1), (2), and (3), one end portion of the gradient magnetic field coil protrudes from one end surface of the static magnetic field generating means.

  According to the present invention, by arranging the wiring material unit on the outer peripheral portion of the gradient magnetic field coil, the space on the inner peripheral side of the gradient magnetic field coil can be secured without being narrowed, and the pattern area of the gradient magnetic field coil can be set in the axial direction. Can be extended.

  Accordingly, the axial length of the static magnetic field generating means can be shortened to substantially the same length as the gradient magnetic field coil, and the gradient magnetic field pattern region can be expanded in the axial direction, so that the linearity of the magnetic field can be ensured.

  That is, according to the present invention, a gradient coil that can shorten the axial length of the container and reduce linearity of the gradient magnetic field in order to reduce the feeling of pressure felt by the subject, and a magnetic field using the same A resonance imaging apparatus can be realized.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is an overall schematic configuration diagram of an MRI apparatus to which the present invention is applied.

  In FIG. 1, an MRI apparatus is for obtaining a tomographic image of a subject using a magnetic resonance phenomenon, and includes a static magnetic field generation means 1, a gradient magnetic field generation means 102, a transmission system 103, and a reception system 104. A signal processing system 105, a control unit 106 that controls the operation of the static magnetic field generating means 1, a central processing unit 107, and an operation unit 108.

  The static magnetic field generating means 1 generates a uniform static magnetic field in a direction perpendicular to or parallel to the body axis around the subject 108 from a magnet arranged in a wide space around the subject 108. .

  The gradient magnetic field generating means 102 includes a gradient magnetic field power supply 110 and a gradient magnetic field coil 2, and generates gradient magnetic fields in three axes directions of the X axis, the Y axis, and the Z axis in an imaging space where the subject 108 is arranged. To do. The imaging cross section of the subject 108 is set by applying this gradient magnetic field.

  The transmission system 103 includes a high frequency oscillator 111, a modulator 112, a high frequency amplifier 113, and a high frequency irradiation coil 3. This transmission system 103 is output from the high-frequency oscillator 111 in order to excite the atomic nuclei constituting the biological tissue of the imaging cross section of the subject 108 set by the gradient magnetic field generating means 102 to cause nuclear magnetic resonance. The high frequency pulse is supplied to the high frequency amplifier 113 via the modulator 112. Then, after being amplified by the high-frequency amplifier 113, the high-frequency pulse is supplied to the high-frequency irradiation coil 3 installed close to the subject 108 to irradiate the subject 108 with a high-frequency pulse.

  The receiving system 104 includes a high-frequency receiving coil 115, a receiving circuit 116, and an analog / digital (hereinafter referred to as “A / D”) converter 117. Then, an NMR signal, which is an echo signal due to magnetic resonance of the nuclei of the biological tissue of the subject 108 due to the electromagnetic waves irradiated from the high-frequency irradiation coil 3 of the transmission system 103, is placed near the subject 108. Detect with.

  The NMR signal detected by the high frequency receiving coil 115 is input to the A / D converter 117 via the receiving circuit 116 and converted into a digital signal.

  The A / D converter 117 sends the signal to the signal processing system 105 as the collected data sampled at the timing according to the command from the control unit 106.

  The control unit 106 operates under the control of the CPU 107, and repeatedly generates slice encoding, phase encoding, and frequency encoding gradient magnetic fields and high-frequency magnetic field pulses in a predetermined pulse sequence. Then, the control unit 106 sends various commands necessary for acquiring tomographic image data of the subject 108 to the gradient magnetic field generating means 102, the transmission system 103, and the reception system 104.

  The signal processing system 105 includes a CPU 107, a signal processing device 118, a memory 119, a magnetic disk 120, an optical disk 121, and a display (display means) 122.

  The CPU 117 performs Fourier transform and control of the sequencer 106 on the collected data. Further, the signal processing device 118 performs processing necessary for reconstructing correction calculation and collected data into a tomographic image.

  The memory 119 stores a program of a time-lapse image analysis process and a designated measurement sequence, parameters used at the time of execution, and the like, and measurement parameters obtained in advance measurement performed on the subject. Collected data from the NMR signal detected by the receiving system 104 and an image used for setting the region of interest are temporarily stored, and parameters for setting the region of interest are recorded.

  The magnetic disk 120 and the optical disk 121 are data storage units for storing the reconstructed image data. The display 122 performs image reconstruction calculation using the NMR signal detected by the receiving system 104 and displays the image.

  The operation unit 108 includes a trackball, a mouse, a keyboard, and the like, and is used to input control information for processing performed by the signal processing system 105.

  Images obtained by reconstructing NMR signals detected by the receiving system 104 are sequentially displayed on the display 122. The position and angle of the next imaging are set by the operation unit 108 on the continuously displayed images. The set information is displayed on the display 122.

  Next, the gradient coil 2 of the present invention applied to the above-described MRI apparatus will be described.

  FIG. 2 is a schematic configuration diagram of a portion where the gradient magnetic field coil 2 of the MRI apparatus shown in FIG. 1 is arranged.

  In FIG. 2, the subject is placed in the uniform magnetic field region 50 and laid on the bed 4. The gradient coil 2 is fixed between the static magnetic field generating means 1 and the uniform magnetic field region 50.

  The high frequency magnetic field coil 3 is fixed between the uniform magnetic field region 50 and the gradient magnetic field coil 2. The wiring material unit 30 is fixed to the outer peripheral side of the end of the gradient magnetic field coil 2.

  That is, as shown in FIG. 3, the end portion of the cylindrical gradient magnetic field coil 2 protrudes from the end face of the static magnetic field generating means 1, and the wiring member unit is annularly formed on the outer peripheral side of the protruding portion of the gradient magnetic field coil 2. 30 is arranged.

  Here, the wiring material unit is a unit for electrically connecting the main coil and shield coil of the gradient magnetic field coil 2.

  The gradient magnetic field coil 2 and the wiring material unit 30 constitute a gradient magnetic field coil device.

  The gradient magnetic field coil 2 has a substantially cylindrical shape, and includes a main coil that applies a gradient magnetic field to the X, Y, and Z axes, and a shield coil that cancels the leakage magnetic field of the main coil.

  FIG. 4 is a schematic perspective view of the X coil, which includes main coils 11, 12, 13, and 14 and shield coils 21, 22, 23, and 24 that cancel the leakage magnetic field of the main coils 11 to 14.

  The Y coil is obtained by rotating the X coil shown in FIG. 4 by 90 degrees and has the same configuration as the X coil.

  These eight coils 11 to 14 and 21 to 24 are electrically connected in series to each other by a wire processed from a conductor such as copper or a plate-like wiring material. When this series connection is performed, wiring members 31 and 32 (shown in FIG. 5) arranged in the wiring unit 30 are used.

  The wiring members 31, 32 connect the coils 11, 12, 21, 22, and 13, 14, 23, 24 connected in series, and the terminals 32A and 32B of the wiring member 32 are connected to gradient magnetic field coils (GC). ) A terminal (not shown) connected to the GC power supply 110 that supplies power to 2 is connected to the wiring member 32. Connection between the coils is performed using a bolt or the like (not shown).

  FIG. 6 is a partial schematic cross-sectional view of the end portion of the gradient coil. As shown in FIG. 6, the end portion of the cylindrical gradient magnetic field coil 2 protrudes from the end face of the static magnetic field generating means 1, and the wiring member unit 30 is annularly formed on the outer peripheral side of the protruding portion of the gradient magnetic field coil 2. The wiring members 31 and 32 are connected to the shield coil 21 and the like.

  By arranging this configuration, that is, the annular wiring member unit 32 on the outer peripheral portion of the GC 2, the space on the inner peripheral side of the gradient magnetic field coil 2, that is, the space where the subject 108 is arranged is secured without narrowing. In addition, the gradient magnetic field pattern region of GC2 can be expanded in the axial direction.

  Therefore, the axial length of the static magnetic field generating means 1 can be shortened to substantially the same length as that of the gradient magnetic field coil 2 and the pattern area of the GC 2 can be expanded in the axial direction, so that the linearity of the magnetic field can be ensured.

  That is, according to the present invention, a gradient coil that can shorten the axial length of the container and reduce linearity of the gradient magnetic field in order to reduce the feeling of pressure felt by the subject, and a magnetic field using the same A resonance imaging apparatus can be realized.

FIG. 7 is a schematic perspective view of the wiring unit 30.
In FIG. 7, the wiring members 31 and 32 are fixed in the wiring unit 30 at regular intervals with an insulating material such as thermoplastic polyimide interposed therebetween. The wiring members 31 and 32 form a wiring unit 30 by molding with an epoxy resin or the like.

  In FIG. 7, the wiring members 31 and 32 are connected to the conductor of the gradient magnetic field coil 2 by bolts or the like at the A part.

  Although not shown, the wiring unit 30 includes wiring materials for the Y coil and the Z coil, and a pipe for introducing a cooling medium into the gradient magnetic field coil 2 when cooling is required.

FIG. 8 is a diagram showing the direction of current in the wiring unit 30.
In FIG. 8, a current supplied from a power source for GC (not shown) flows from the terminal 32B of the wiring unit 30 to one end 32D of the wiring member 32, and the coil 13 in the gradient magnetic field coil 2 from this one end 32D, 14, 23, 24.

  Then, the other end 31B flows from one end 31A of the wiring member 31 of the wiring unit 30, and the coils 11, 12, 21, and 22 in the gradient magnetic field coil 2 flow from the other end 31B. Thereafter, the current flows from the other end 32C of the wiring 32 of the wiring unit 30 to the terminal 32A.

  In the above-described example, the wiring members 31 and 32 are formed as a wiring unit and separated from the gradient magnetic field coil 2, but may be integrated with the gradient magnetic field coil 2.

  However, when the gradient magnetic field coil 2 is inserted into the magnet bore, it is necessary to insert it from the direction opposite to the side on which the wiring member is fixed.

1 is an overall schematic configuration diagram of a magnetic resonance imaging apparatus to which the present invention is applied. It is a schematic block diagram of the part by which the gradient magnetic field coil in a magnetic resonance imaging apparatus is arrange | positioned. It is a schematic perspective view of the cylindrical gradient magnetic field coil end part of this invention. It is a figure which shows the gradient magnetic field coil in this invention. It is a figure which shows the terminal processing structure of the gradient magnetic field coil in this invention. It is a partial schematic sectional drawing of the gradient magnetic field coil in this invention. It is an external view of the wiring unit of the present invention. It is a figure which shows the flow of the electric current in the wiring unit of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Static magnetic field generation means 2 Gradient magnetic field coil 3 High frequency magnetic field coil 4 Bed 30 Wiring unit 31, 32 Wiring material 50 Uniform magnetic field area 102 Gradient magnetic field generation means 103 Transmission system 104 Reception system 105 Signal processing system 106 Control part 107 Central processing unit 108 Operation part

Claims (6)

Used in a magnetic resonance imaging apparatus having a substantially cylindrical static magnetic field generating means, having a cylindrical gradient magnetic field coil disposed on the inside of the cylinder of the static magnetic field generating means, and supplying a current from a gradient magnetic field power source In the gradient coil device,
A gradient magnetic field coil device, wherein a wiring material unit for connecting the gradient magnetic field coil and a gradient magnetic field power source is disposed along the outer periphery on one end portion side on the outer periphery on one end portion side of the gradient magnetic field coil. .   2. The gradient magnetic field coil apparatus according to claim 1, wherein the wiring member unit is formed integrally with the gradient magnetic field coil.   3. The gradient magnetic field coil device according to claim 1, wherein one end of the gradient magnetic field coil protrudes from one end surface of the static magnetic field generating means. A substantially cylindrical static magnetic field generating means, a gradient magnetic field generating means that has a cylindrical gradient magnetic field coil disposed on the cylinder inner side of the static magnetic field generating means and applies a gradient magnetic field to a subject, and a gradient magnetic field generating means A gradient magnetic field power source for supplying a current to the subject, an irradiating means for applying a high-frequency pulse that causes a nuclear magnetic resonance phenomenon to the subject, a receiving means for detecting an echo signal emitted from the subject, and a detecting means In a magnetic resonance imaging apparatus comprising an operation control means for performing an image reconstruction operation using an echo signal and controlling an imaging operation, and a display means for displaying an image,
A magnetic member characterized in that a wiring material unit for connecting the gradient magnetic field coil and the gradient magnetic field power supply is disposed along the outer periphery on the one end portion side on the outer periphery on the one end portion side of the cylindrical gradient magnetic field coil. Resonance imaging device.   5. The magnetic resonance imaging apparatus according to claim 4, wherein the wiring member unit is formed integrally with the gradient magnetic field coil.   6. The magnetic resonance imaging apparatus according to claim 4, wherein one end of the gradient magnetic field coil protrudes from one end surface of the static magnetic field generating means.

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